WhatfettleOne CSV, thirty stories: 9. Yearly

This is day 9 of "One CSV, 30 stories":http://blog.whatfettle.com/2014/10/13/one-csv-thirty-stories/ a series of articles exploring "price paid data":https://www.gov.uk/government/statistical-data-sets/price-paid-data-downloads from the Land Registry found on GOV.UK. The code for this and the other articles is available as open source from "GitHub":https://github.com/psd/price-paid-data

I'd declared "yesterday's post":http://blog.whatfettle.com/2014/10/25/one-csv-thirty-stories-8-heatmap-meh/ a bit meh, but on reflection it highlighted an interesting anomaly, an intensification of the number of transactions around the £250k price-point, but how does that relate to the overall number of transactions?

We can quickly crate a list of the number of transactions per-year by cutting the date from the price-paid CSV, stripping off the @-MM-DD@ part and counting the number of lines for each year:

bc. cut -f2 < pp.tsv | sed 's/-.*//' | sort | uniq -c | awk '{print $2 "⋯" $1}' bc. 1995 766098 1996 930498 1997 1061710 1998 1027447 1999 1177016 2000 1114549 2001 1231181 2002 1337684 2003 1246935 2004 1261448 2005 1052475 2006 1315598 2007 1262214 2008 644178 2009 619394 2010 657886 2011 655603 2012 654353 2013 792356 2014 516948 Turning once again to gnuplot, our current hammer of choice. The following script: bc. set terminal png font "helvetica,14" size 1600,1200 transparent truecolor set output "/dev/stdout" set key off set style data histogram set style fill solid border set ylabel "Number of transactions" set format y "%.01s%c" set yrange[0:*] set xlabel "Year" plot "/dev/stdin" using 2:xtic(1) lc rgb "black" turns the figures into a histogram: Number of transactions by year

Which illustrates how the increasing intensity of yesterday's heatmap at the lower price bands comes at a time when the volume of transactions are half of their peak. This is either an interesting lead, or raises questions over how the data is collated.

This isn't the post I worked on today, and changes the direction of "tomorrow":http://blog.whatfettle.com/2014/11/01/one-csv-30-stories-10-loess-curve/'s post. That's my being agile, innit?